Induction furnace



Sept. 16, 1958 o. JUNKER INDUCTION FURNACE Filed Nov. 7, 1955 JNVENTOR.-

JUNKER,

2,852,587 INDUCTION FURNACE Otto Junker, Lammersdorf, Germany, assignor to Ajax Engineering Corporation, Trenton, N. J., a corporation of New Jersey Application November 7, 1955, Serial No. 545,399 4 Claims. (Cl. 13-27) The invention relates to electric induction furnaces, and relates more particularly to an improvement in the coil support for such induction furnaces, especially coreless metal melting furnaces operating in the low frequency or medium frequency spectra.

It is an object of the invention to provide for the holding of the windings of the coils in the proper position relative to each other, at about an equal height, to counteract any axially acting shortening or lengthening forces that the coil may be subjected to.

lt is another object of the invention to provide for such holding of the windings in an elastic manner.

It is a further object of the invention to subject the windings of the coils resiliently to compression pressure in the axial direction.

Generally speaking, this is accomplished by applying the force of resilient means against one end of the coil pressing it towards the other end.

With the above and other objects of the invention in View, the invention consists in the novel construction, arrangement and combination of various devices, elements and part, as set forth in the claims hereof, one embodiment of the same being illustrated in the accompanying drawings `and described in the speciiication.

in the accompanying drawings,

Fig. l is a vertical sectional view of Van induction furnace provided with a coil support in accordance with the invention, taken on line 1-1 of Fig. 2;

Fig. 2 is a horizontal sectional view taken on line 2-2 of Fig. 1; and

Fig. 3 is a large scale elev-ational view, partly in section, showing a detail illustrated in Fig. l.

In carrying the invention into effect in one of the embodiments which has been selected for illustration in the accompanying drawings and for description in this speciication, there is provided -a furnace 11 that has a crucible 12 which is composed of refractory material, such as a ramming mixture. Heat insulation members 13 and 14 surround the top and vbottom portions of the crucible 12, A frame, generally indicated at 16 supports the crucible 12. It is formed yof angle irons 17 and of sheet met-al. A magnetic 4structure 18 is provided that includes a series of laminated iron yokes 19, and the laminated yokes 19 are connected to the frame 16 by means of upper sheet met-al strips 21 and lower sheet metal strips 22. The laminated yokes 19 are arranged along a cylinder about the axis of the crucible 12, land 'are spaced from yeach other at uniform distances along the cylinder orbit, and have their axes arranged radially intersecting the axis of the crucible 12.

Each laminated yoke 19 carries near its upper end a lug 23, and near its lower end a lug 24, that projects towards the interior of the crucible 12. A cylindrical induction coil 26 surrounds the major portion of the external surface of the -crucible 12 and is disposed in the space that is defined between said external surface of the crucible 12 and the innermost surfaces of the laminated yokes 19. The coil 26 rests with its annular bottom surface on a support, for instance on a raised portion 27 of the lower insulation member 14, and extends with its upper end towards the lower portion of the upper insulating member 13.

A plurality of means such as resiliently biased movable nited States Patent O ice yokes 2S are provided to compress the coil 26 downwardly, against the support 27. A movable yoke 28 is connected to each laminated yoke 19, and comprises a pressure transfer member such as a shoe 29 that rests against the upper annular surface 31 of the coil 26. Each shoe 29 is secured to `a rod 32 that is guided for vertical reciprocal movement in two brackets 33 and 34 of each laminated yoke 19. At the lower end, each of the rods 32 has adjustably positioned a terminal member such as a nut 36, and `a compression spring 37 is disposed between the lower bracket 34 and the nut 36, and urges the nut 36 and thereby the rod 32 and the shoe 29 downwardly. Each shoe 29 is thereby resiliently pressed downwardly onto the top surface 31 of the coil 26, exerting a downward pressure against the coil.

As the laminated yokes 19 are uniformly spaced from each other around the coil 26, the shoes 29 will exert a downward pressure at regular intervals, and the intervals are chosen sufficiently small so that thereby the coil 26 will be subjected to compression throughout its circumference.

The compression of the coil 26 exerted by the springs 37, assures that the windings of the coil will be in proper position relative to each other, when the coil is shortened or elongated, for instance Iby heat or other forces Iapplied thereto, This has the advantage that all of the windings of the coil will be subjected to substantially the same uniform stresses.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire to ybe secured by Letters Patent, is as follows:

1. An induction furnace operating in the spectrum of low and middle frequencies, -comprising in combination, a crucible, an electric coil encircling said crucible, a series of laminated yokes spaced from each other uniformly along the periphery of said coil, and means operable for resiliently compressing axially the windings of the coil, comprising a stationary support for said coil and resiliently movable means connected to each laminated yoke biased to exert pressure onto said coil towards said station-ary supports.

2. In an induction furnace, having an upright crucible and a coil encircling the external surface of said crucible and a plurality of laminated yokes spaced uniformly about said coil, in combination, a support below said coil, and a pressure transfer member connected to each laminated yoke and guided for vertical movement and engaging the top of the coil, and spring means urging each pressure transfer member resiliently in a downward direction.

3. An induction furnace, as claimed in claim 2, together with, a bearing connected to each laminated yoke, a vertical rod guided for vertical reciprocal movement in said bearing, said pressure transfer member being secured to said rod and movable therewith, and a spring biasing said rod downwardly.

4. An induction furnace, as claimed in claim 2, each pressure transfer member having an elongated portion disposed substantially radially of the coil, said members being -spaced uniformly about the periphery of the annular top surface of said coil and engaging said top surf-ace.

References Cited in the le of this patent UNITED STATES PATENTS 

